Telecommunications networks provide a medium for communicating signals between communication devices. For example, the public switched telephone network (PSTN) typically carries signals representing voice communications between telephones coupled to the telephone network. The telephone network can also carry signals that represent other types of communications, such as data between computer modems or other communication devices.
Another typical telecommunications network is the cable network. The cable network conventionally carries signals representing video programming from a head end to subscriber's equipment, e.g., a television or a set top box.
The cable industry has recently experimented with bi-directional communication over existing cable networks. Bi-directional communications allow cable networks to provide, for example, video-on-demand, Internet access and telephony services over existing cable networks. These services are implemented by connecting subscriber's equipment to the cable network via a cable modem or other appropriate communications device.
With the conventional telephone system, the communication devices, e.g., telephones, are typically powered by the telephone network. Since the telephone network uses batteries to back-up line power, a conventional telephone functions properly even if power is lost at the subscriber's location.
One problem with conventional approaches to cable modems is providing power to the modems. Cable modems can either be powered from a power source located at the subscriber's location or powered using network power. When local power is used, if the subscriber loses power, the cable modem ceases to function. This reduces the effectiveness of the cable company in competing with the telephone companies to provide new services to subscribers. However, powering cable modems with network power is not a trivial matter because cable modems consume large quantities of power.
Power constraints on communications devices are also prevalent in other communications networks. For example, communications devices that rely on battery power have limited effectiveness due to power consumption issues. In wireless networks, wireless terminals, e.g., cellular telephones, typically run on battery power. One problem with these communication devices is that the battery life is short due to power requirements to run the wireless terminal in standby mode.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a communication device with reduced power requirements.